Insight into the Structure–Activity Relationship of Delafossite Catalysts for Enhanced Peroxymonosulfate Activation and Pollutant Degradation

Delafossite compounds (general formula ABO2) have gained attention as promising catalysts for advanced oxidation processes (AOPs) due to their excellent substrate compatibility. However, the specific role of redox-active B-site metal centers in their catalytic mechanisms remains insufficiently elucidated. In this work, delafossite-type CuFeO2 and CuMnO2 catalysts were successfully synthesized via a one-step hydrothermal method and applied to peroxymonosulfate (PMS) activation to degrade ofloxacin (OFX) and methylene blue (MB). Catalytic performance assessments demonstrated that Mn substitution at the B site markedly enhanced the removal efficiency of OFX. Mechanistic studies involving structural characterization (XRD, BET, XPS) and quenching tests revealed that the enhanced activity originates from the promoted self-decomposition of PMS facilitated by the incorporated Mn, which boosts the formation of radical species (•OH and SO4•−) due to the improved electrical conductivity resulting from manganese’s multivalent nature. By clarifying the influence of the B-site metal electronic structure, this study provides fundamental insights into PMS activation mechanisms and informs the rational design of highly efficient and stable delafossite-based catalysts.